<!DOCTYPE HTML>
<html>
<body>
<div class="scrollTop" style="overflow:hidden; width:200px; height:200px;">
  <div style="margin:70px 20px; opacity:0.5; height:400px; background:yellow;">
    <div style="position:absolute; background:yellow; width:50px; height:100px; top: 0; left:50px;">
    </div>
  </div>
</div>
<script src="scrolling.js"></script>
</body>
</html>
